The problem seems to be not in the r30302 itself, but in the switch from putsxy() to puts_style_xyoffset().
I don't get why the latter uses the space char width to calculate the x offset. Same with the space_width var in skin_display.c, to be honest.
Is it from the old fixed-width-only days? There must be a less square way to calculate the x pos.

yeah, that's pretty much what I guessed was the issue.
There are a few ways to possibly fix this, the best would be cleaning up the puts() API so there is a pixel based putsxy which allows us to set a style, otherwise possibly anotherfunction to just set the draw style.. dunno.

Testing on r30334 with the above patch on sansa e200v1 and default settings:

on rolo, I see some extraneous characters. It looks like this: ( s/-/ / )

ROLO...
Loading
-----------------------ocessor...

The "o" is not complete, but is cut-off - only the right half of the character is displayed. The cut-off "o" appears to start at approximately mid-screen.

In firmware/rolo.c - line 259 "Waiting for coprocessor..." is written to the screen. Line 264 writes an equal number of space characters to the same line to clear what was written. Apparently, this will no longer work if the space character is not the same width as the text characters.

After you've spend a night cleaned up one of ugliest code parts I've seen in rockbox so far... cursing on irc like a drunk sailor?
I'm afraid nobody will submit the rolo patch after that :) because such a tiny addition to your work looks pity.

I mean we all have some skill to replace " " with "M". Some (maybe) can even just clear it up. But the history should remember you alone.
And if you spend just 19 seconds more, it will.
Fame, money, easy chicks -- I don't understand how all that can't motivate you.

like you said, when I spend half the night arguing in IRC over bullshit I dont have very much motivation to work outside of things I persoanlly find interesting. cleaning up old API's not in the things that I could consider being interesting :)
fixing rolo wont be an issue but even with that done this isnt quite finished so not commitable yet

Yeah, I knew it's couldn't be the tiny rolo tweak, it's the perfectionism...
Now it's a weird situation:
1) you've fixed the bug, a rather noticeable one for themes with centered 14+ pt font.
2) you've made the api much more sane. not 100%, but dear god, it at least makes sense now.
3) yet some parts will benefit from more cleanup.

To me it looks like this work is worth to be committed with a comment that it needs more cleanup.
If you don't commit it, a dev with both the skill and interest might simply never come, and the bug will live on.
I honestly tried cleaning the api before you, and I couldn't do even the half of your work.

Not to mention your moral obligations to people of earth -- while r30302 didn't create the bug, it did revealed it. Would be a nice manner to kill it...
You said you can't work if uninterested. Well, don't anymore. Your patch doesn't solve world hunger, it fixes a bug.

Please click on the screenshot again. If you think this is how Rockbox should look like, don't commit your work, ok.

no, this bug doesnt need fixing for 3.10, it appears you two are the only people to notice the change and it isnt a trivial fix. Zagor has taken over the lcd api rework and will hopefully fix this bug soonish